Method of sizing photographic paper and resultant product



2,739,062 Patented Mar. 20, 1956 METHOD OF SIZING PHOTOGRAPHKC PAHER ANDRESULTANT PRODUCT William H. Griggs and Warren T. Heard, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey No Drawing. Application January 2, 1953,Serial N 0. 329,438

Claims. CI. 95-88) This invention relates to a new and improved methodof sizing paper for photographic purposes and the resultant newphotographic paper product. More particularly this invention relates toa new method of the class described and photographic paper productwherein the paper product is characterized by being particularlysuitable for accepting certain types of photographic coatings.

It is well known in the paper art that many of the uses to which paperis put require that the paper fibers be at least partially non-absorbenttoward liquids, or in certain instances the absorbency is controlled.This has been accomplished by treatment of the paper fibers referred toas sizing. One method of sizing in extensive use apparently involves theapplication of a gelatin or glue coating to the surface of the paper.The gelatin may contain other materials such as starch fillers and thelike, as will be discussed hereinafter. Such type of sized paper hasbeen extensively produced and much of it used for photographic purposes.That is, the sized paper is overcoated with various photographiccoatings such as emulsion coatings and the like. However, in recentyears in some instances difliculties have been experienced from thephotographic standpoint, such as instability of photographic coatings orcomponents therein.

Investigations indicate that certain carbonyl compounds or the like inthe gelatin sizing may migrate from the sizing or otherwise enter thephotographic layers and adversely affect some couplers, or developers insaid layers. In other Words, the paper sizing may directly or indirectlybe a factor in reducing the effectiveness of the photographic paperproduct or otherwise causes difficulty such as the obtaining ofunsatisfactory quality when using the product. It is therefore apparentthat provision for correcting or minimizing the aforesaid difiicultiesrepresents a highly desirable result.

After substantial investigation we have found paper sizing materials anda method of paper sizing as will be described in detail hereinafter,which while giving a paper photographic product of substantially thesame appearance and having as good or better properties asconventionally sized, represents a distinct improvement over the priorart in that our new method and sized product may be readily overcoatedwith numerous diflerent type layers containing various developers,couplers, etc. without difficulties of the type referred to above.

This invention has for one object to provide a new method of sizingpaper for photographic uses. Another object is to provide as a newproduct a photographic paper sized in a special manner. Still anotherobject is to provide a photographic paper sized or coated with one ormore layers of sizing materials which arerelatively non-injurious towardcertain components of photographic coatings. Still another object is toprovide a new composite photographic paper product made up of aplurality of elements including paper base, gelatinpolymer size and oneor more photographic layers, all of which elements are relativelycompatible. Other objects will appear hereinafter.

As indicated above, there were certain instances in connection withphotographic papers prepared by prior art procedure where photographiclayers containing couplers, developers or the like, of a type to bereferred to in detail hereinafter, were not as effective as they shouldbe, or the layers were otherwise impaired. We have found that the causeof such difiiculties may be due to a substantial extent to the gelatinsizing containing an aldehyde such as formaldehyde. That is, thisaldehyde which has been commonly added to gelatin may migrate into thephotographic layer or otherwise adversely affect such layers containingdevelopers, couplers and the like. Apparently in the prior art it hasheretofore been regarded as necessary or desirable to put rathersubstantial amounts of formaldehyde in gelatin in order to render thegelatin satisfactory for use as a sizing. That is, the art is repletewith information relative to formaldehyde treatment of gelatin so thatgelatin sizes commercially used may contain aldehyde.

We have found, in accordance with the present invention, that it ispossible to avoid the use of formaldehydetreated gelatin therebyobviating or minimizing difliculties from the photographic standpointdiscussed above. That is, in general in accordance with our invention, agood grade of paper base may be sized with a gelatin(CHCsH5-CH2CHCONH2-CHCOO(NH4) a: combination where(-CHCOH5-CH2CHCONH2CHCOO; NI-Li) 3:

represents a polymer in which said monomer is repeated x times. Thisgives a sizing of comparable physical qualities or better qualities thanthose obtained by prior art gelatin sizes. Sized photographic paper isthen overcoated with photographic coatings such as emulsion coatings andthe like containing various developers, couplers, either alone or incombination with any of the usual sensitive silver salts. This productmay then be further overcoated with additional layers of the sizeaforementioned or additional photographic layers. All of the aboveprocedure may be carried out on the same equipment that has beenpreviously used for applying conventional sizing and coating layers. Theresultant product in appearance, physical properties and the like, isthe same as existing photographic paper stock but possesses improvementin that the paper product of the present invention is more stablephotographically as already discussed as respects developer or couplercomponents.

The chemical compound referred to above may be prepared by reacting anunsaturated hydrocarbon exemplified by styrene, with an anhydride of adibasic acid exemplified by maleic anhydride, followed by the reactionof the polymeric product with ammonia. There are a number of ways ofcarrying outthe reaction and for further details reference may be madeto U. S. Patent Nos. 2,313,565 and 2,698,794. The exact manner offorming the polymeric material, which for convenience herein may bereferred to as SMA (styrene-maleic anhydride-ammonia), is not a part ofor a limitation upon the instant invention.

For a more complete understanding of our invention reference will bemade to certain specific examples which follow and which examples areset forth for illustrating some of the preferred embodiments of ourinvention. In these examples the paper base is preferably of high gradeuncontaminated stock. That is, the paper fibers may come from eitherwood pulp or cotton cellulose and preferably the pulp for the paper isdisintegrated and friabllated in stainless steel, tile-lined or platedequipment in order that the paper stock be free of contamination. Whilethe sizing agent of the present invention may be added to the resultantuniform blend of cellulose fibers Id in water, as will be apparent fromthe description which follows, we prefer in most instances to apply asurface or tub sizing in addition to, or in place of, sizing in thebeater. The relatively pure paper stock as just described is subjectedon the continuous moving wire of paper making machines to the process ofwater removal, the water drainage being assisted by suction boxes andpressure rolls until the paper base sheet is obtained at the end of themoving wire. This sheet then traverses the dryer stacks which are madeup preferably of heated revolving chromium plated iron drums and aftercalendering, the paper stock is wound into rolls and is ready forfurther treatment in accordance with the present invention. in thedescription set forth in the examples which follow it will be assumedthat a suitable high grade paper has been prepared along the linesaforementioned. This paper may contain baryta or the like components asmay be conventional, although such features are only briefly mentionedherein.

Example I In accordance with this example, approximately 42 parts byweight of gelatin was soaked in 200 parts by weight of cold water forabout one hour. Solution of the gelatin was accomplished by heating toabout 115 F. and adding approximately 745 parts of hot water. There wasthen added 125 parts by weight of a aqueous solution of being verycareful to keep the pH between 4.5 and 5. This gelatin-SMA size solutionis then cast on a support and dried. It will be noted that the resultantgelatin- SMA film so obtained is insolubilized to a degree entirelycomparable to the prior art type of gelatin which has been formed from asolution containing formaledhyde, chromic chloride and the like.

The gelatin-SMA solution of the present invention may be used to sizephotographic paper stock. That is, the photographic paper stock may bepassed under or over a coating roll or other device for applying a thinlayer of size to the paper base. The sized paper may be partially orfully dried by passing through a chamber in which warm air iscirculated, or the sized paper, for example with limited drying,promptly passed to further coating operations where photographic layersare applied as will be described in greater detail in examples whichfollow.

It will be observed that while in the above example the incorporation ofwas to the extent of about (based on the weight of the gel), this is notintended to restrict the concentration at that level. We have found thatconcentrations of SMA as low as 10% are quite useful as areconcentrations as high as However, around 20 to 35% seems quitesatisfactory and there is usually no need of incorporating higheramounts. In instances where the photographic paper sized in accordancewith the present invention is to be further coated with layerscontaining developers or the like, it may be desirable to use loweramounts of SMA, say of the order of about 10% as just mentioned.

As already pointed out, the pH during the addition of the small amountof acid, say the addition of a limited quantity of 0.1 N-HCl. Also thestability of the gelatinmixture may be improved by lowering the pH toabout 3.5 where higher amounts of the polymeric material are used, as ininstances where 4050% of the polymer is being incorporated into thegelatin.

Example II it was caiendered and then over-coated with a photor graphiclayer.

Example 111 in accordance with this example, paper of the type describedwas passed through a tub size pan immediately after the first dryingsection on the paper machine. The size pan contained a gel-SMA sizecomparable in makeup to that of Example I. The SMA concentration (basedon gel weight) can be varied in accordance with Example I. The gelconcentration can be varied from 2-5 parts per parts solution.

Example IV In accordance with this example photographic paper of a typeas already described, after being sized with gelatin- SMA and suitablyfurther processed, was then overcoated with a photographic layer. Inthis instance this layer contained one or more of the followingdeveloping agents: 3,4-dihydroxy diphenyl, 2,5-dihydroxy diphenyl,5,6,7,8- tetrahydronaphthohydroquinonc, and 2,3-dihydroxy diphenyl. inaddition, the product contained certain amounts of the usual silverhalide components and antiabrasion overcoatings were applied.

Subsequent use, observation and test of this photographic paper sized inaccordance with the present example, indicated that even after severalmonths this product was stable, there being no evidence of developerdisintegration.

Example V In accordance with this example, paper of the type aireadydescribed was suitably coated with a baryta coating and thereafter sizedwith gelatin-SMA size of the present invention. The sized coating wassuitably processed by calendering, after which a plurality of coatingswere applied, which coatings contained one or more of the magenta andother couplers described in U. S. Patent No. 2,322,027, such as forexample:

l-p-sec. amylphenyl-3-n-amyl-5-pyrazolone 2-cyanoacetyl-5-(p-sec.amylbenzoylamino)-coumarone 2-cyanoacetylcoumarone-5-(n-n-amyl-p sec.amylsulfanilide) Z-cyanoacetylcoumarone-S-(N-n-amyl-p-tert.amylsulfanilide) 2-cyanoacetylcoumarone-S-sulfon-N-n-butylanilide2-cyanoacetyl-5-benzoylamino-coumaroneZ-cyanoacetylcoumarone-S-sulfondimethylamide2-cyanoacctylcoumarone-S-sulfon-N-methylanilide 2-cyanoacetylnaphthalenesulfon-N-methylanilide Z-cyanoacetylcoumarone-5-(N-- -phenylpropyl) ptert.

amylsulfonanilide l-p-laurylphenyl-3-methyl-5-pyrazolone1-fl-naphthyl-3-amyl-S-pyrazolone 1-p-nitrophenyl-3-n-amyl-5-pyrazolone1-p-phenoxyphenyl-3-n-amyl-5-pyrazolone l-phenyl-3-n-amyl-5-pyrazolone V1,4-phenylene bis-3- l-phenyl-S-pyrazolone)N-amyl-p-benzoylacetarninobenzenesulfonateN-(4-anisoylacetaminobenzenesulfonyl) N benzyl mtoluidineN-(4-benzoylacetaminobenzenesulfonyl)-N benzyl mtoluidine When we referto magenta and yellow couplers we refer to chemical compounds of thetype just enumerated.

The product was then further finished in conventional manner.Observation and tests at the end of six months indicated that thecouplers were still in an efficient, active 90 form and that nosubstantial disintegration or change thereof had occurred.

Example VI In accordance with this example, sizing solutions were madeup as described in Example I except that citric acid, acetic acid, ordilutesulfuric acid were used to adjust the pH of the solution to thelevel described. The sizing solution was applied to the paper asdescribed in Example I with similar results. no

Example VII In accordance with this example, photographic paper stock aspreviously described was sized in a suitable manner with a gelatin-SMAsolution as in Example I. The

sized stock was then overcoated with a sensitized trans- 35 fer materialuseful in photomechanical reproduction processes similar to thosedescribed in U. S. Patent No. 2,596,756. The sizing had no deleteriouseffects on the sensitive materials which are obtained with regularformaldehyde hardened sized paper. 40

It can be seen from the foregoing that we have provided new and improvedphotographic paper product and method for the production thereof, inthat, while the paper product is comparable to the prior art product inall general respects, nevertheless our product exhibits ini- 45provement in that it is relatively free of instability due to prior artsizing. Our product may be made on existing equipment by substantiallythe same technique heretofore used, and in view of the limited amount ofchange thus ammonia, incorporating 10 to 50% by weight of said reactionproduct with gelatin while controlling the pH to less than 5 during saidincorporation to form a polymericgclatin size and then applying saidsize to a surface of a good grade paper, at least partially drying thepaper thus coated, whereby an improved paper for photographicuses isobtained.

2. A process for the manufacture of an improved gelatin coated paperwhich is particularly adapted for use as a base material to receivephotographic coatings, which comprises obtaining a polymeric reactionproduct comprising the product obtained by reacting styrene with maleicanhydride, followed by the reaction thereof with ammonia, incorporatingto by weight of said reaction product with gelatin while controlling thepH to less than 5 during said incorporation to form apolymericgelatinsize, and then applying said size to a surface of a good grade paper, atleast partially drying the paper thus coated, whereby an improved paperfor photographic uses is obtained. I

3. A process for the manufacture of an improved paper which isparticularly adapted for use as a base material to receive photographiccoatings which comprises obtaining a polymeric reaction product havingthe properties of the reaction product obtained by reacting styrene withmaleic anhydride, followed by the treatment thereof with ammonia,incorporating from 40% to by weight of such polymeric reaction productwith gelatin, during said incorporation maintaining a pH below 3.5 byadding a suitable amount of acid to the polymer-gelatin composition,thereafter applying said polymer-gelatin combination to at least one ofthe surfaces of a good grade paper whereby an improved paper forphotographic purposes is obtained.

4. An improved treated paper particularly adapted for receivingphotographic coatings comprising a paper base, a coating on at least oneof the surfaces of said base, said coating being essentiallycomprised'of gelatin having incorporated therewith from 10% to 50% of apolymeric material obtained from the reaction of styrene with maleicanhydride and then with ammonia.

5. An improved photographic material essentially comprised of a paperbase having a coating on at least one of the surfaces of said base,comprising gelatin having incorporated therewith from 10% to 50% of apolymeric reaction obtained by reacting styrene with maleic anhydride,followed by the treatment thereof with ammonia, said gelatin-polymericcoating being. overcoated with a layer containing aformaldehyde-sensitive photographic layer.

required, our invention readily adapts itself to applica- 50 tion toexisting industry.

We claim:

1. A process for the manufacture of an improved gelatin coated paperwhich is particularly adapted for use as a base material to receivephotographic coatings, which comprises obtaining a polymeric reactionproduct comprising the product obtained by reacting styrene with maleicanhydride, followed by the reaction thereof with References Cited in thefile of this patent UNITED STATES PATENTS 1,623,522 Bent Apr. 5, 19272,313,565 McDowell Mar. 9, 1943 FOREIGN PATENTS 676,459 Great BritainJuly so, 1952

5. AN IMPROVED PHOTOGRAPHIC MATERIAL ESSENTIALLY COMPRISED OF A PAPERBASE HAVING A COATING ON AT LEAST ONE OF THE SURFACES OF SAID BASE,COMPRISING GELATIN HAVING INCORPORATED THEREWITH FROM 10% TO 50% OF APOLYMERIC REACTION OBTAINED BY REACTING STYRENE WITH MALEIC ANHYDRIDE,FOLLOWED BY THE TREATMENT THEREOF WITH AMMONIA, SAID GELATIN-POLYMERICCOATING BEING OVERCOATED WITH A LAYER CONTAINING AFORMALDEHYDE-SENSITIVE PHOTOGRAPHIC LAYER.